DE 1200809 describes two ways to prepare chloromethanesulfonic acid chloride. Both use s-trithian as starting material and produce yields of only 51.6% and 61.7%. In addition, the relatively expensive starting material, s-trithian is also required to prepare the desired derivatives. Also, pure products are not obtained by this process. Rather, mixtures of mono- and polychloroalkylsulfonic acid chlorides are produced, which are difficult to separate completely. Also a number of sulfur-containing side products are produced, the waste disposal of which can cause problems.
DE-OS 2545644 discloses a process by which R-Hal compounds are reacted with sulfite salts by phase transfer catalysis in water to give salts of sulfonic acids. In a separate second step, after isolation and drying, the sulfonic acid salts obtained are converted into the corresponding sulfonic acid chlorides by means of a chlorinating agent. Yields of 69% are achieved. In this process, production of the sulfonic acid and chlorination are separated by a drying stage. The disadvantage is that the salt mixture which is used for chlorination has to be extremely dry (s. Organikum 1986, 16th edition VEB, bottom cf p. 422), since residues of the aqueous solvent from the first step lead to a higher consumption of the chlorinating agent and to an increase in the range of secondary products.
This extreme drying of salt mixtures, however, is very difficult to achieve in an industrial process and leads to a time-consuming, cost-intensive drying procedure. Also, the handling of solids is an obstacle to industrial use of the process.